Preheat oven to 350F
Grease and line a 9” x 13” casserole dish. Set aside.
In a large bowl, beat together the butter, oil and sugar until light and completely combined.
Add eggs, one at a time, beating after each addition, then the vanilla extract. Set aside.
In a medium-sized bowl, stir together the flour, baking powder and salt.
Gently fold half of the flour mixture into the butter mixture, then the milk, then the remaining flour mixture.
Pour the batter into your prepared casserole dish and bake for 35-40 minutes, until an inserted toothpick comes out clean.
While the cake is cooling, use a skewer to poke holes all over the cake.
In a large bowl, combine the evaporated milk, sweetened condensed milk and heavy whipping cream until completely combined.
Pour the milk mixture over the cake and then refrigerate until completely cooled. (Overnight is best.)
Once the cake is fully cooled, beat the heavy whipping cream for 4 minutes with an electric mixer, then add the white sugar and vanilla extract and continue to beat for 2-4 minutes until light, fluffy and thick.
Smooth the whipped cream frosting over the finished cake and serve.